Publications by authors named "Marilyn Gatica"

Whole-brain models are valuable tools for understanding brain dynamics in health and disease by enabling the testing of causal mechanisms and identification of therapeutic targets through dynamic simulations. Among these models, biophysically inspired neural mass models have been widely used to simulate electrophysiological recordings, such as MEG and EEG. However, traditional models face limitations, including susceptibility to hyperexcitation, which constrains their ability to capture the full richness of neural dynamics.

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Diversity in biological, social, and environmental factors plays a central role in shaping brain health and disease. Distinct brain disorders frequently exhibit overlapping clinical phenotypes, despite arising from heterogeneous biological and contextual mechanisms. This convergence challenges conventional, population-averaged approaches, which often fail to capture interindividual variability and lead to limited reproducibility, weak translational potential, and inadequate tools for individual-level characterization.

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Transcranial ultrasound stimulation (TUS) is a promising non-invasive neuromodulation modality, characterized by deep-brain accuracy and the capability to induce longer-lasting effects. However, most TUS datasets are underpowered, hampering efforts to identify TUS longevity and temporal dynamics. This primate case was studied awake with over 50 fMRI datasets, with and without left anterior hippocampus TUS.

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Objective: Despite the growing interest in transcranial focused ultrasound stimulation (TUS), our understanding of its underlying mechanisms remains limited. In this study, we aimed to investigate the effects of TUS on several functional magnetic resonance imaging metrics by considering their latency, duration, and relationship with applied acoustic pressure.

Materials And Methods: We recruited 22 healthy volunteers and used a pre- vs post-TUS protocol.

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In recent decades, neuroscience has advanced with increasingly sophisticated strategies for recording and analysing brain activity, enabling detailed investigations into the roles of functional units, such as individual neurons, brain regions and their interactions. Recently, new strategies for the investigation of cognitive functions regard the study of higher order interactions-that is, the interactions involving more than two brain regions or neurons. Although methods focusing on individual units and their interactions at various levels offer valuable and often complementary insights, each approach comes with its own set of limitations.

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Low-intensity transcranial ultrasound stimulation (TUS) is a noninvasive technique that safely alters neural activity, reaching deep brain areas with good spatial accuracy. We investigated the effects of TUS in macaques using a recent metric, the synergy minus redundancy rank gradient, which quantifies different kinds of neural information processing. We analyzed this high-order quantity on the fMRI data after TUS in two targets: the supplementary motor area (SMA-TUS) and the frontal polar cortex (FPC-TUS).

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Article Synopsis
  • Non-invasive neuromodulation, particularly transcranial focused ultrasound (FUS), holds potential for brain interventions but requires further understanding of its effects.
  • The study involved 22 healthy volunteers to explore the temporal dynamics of FUS, comparing brain activity before and after stimulation in two different brain areas: the right inferior frontal cortex and the right thalamus.
  • Results showed that FUS effects are time-sensitive and connected to brain areas related to the stimulation, with notable behavioral changes linked to the right inferior frontal cortex, influenced by the acoustic pressure applied during FUS.
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  • Low-frequency transcranial ultrasound stimulation (TUS) can influence brain function with high precision and deep target reach, but the duration and dynamics of its effects are not well understood.* -
  • In a study with three monkeys, TUS was applied to specific brain areas, and resting-state fMRI scans were conducted to analyze changes in brain connectivity over time and between individuals.* -
  • The findings revealed that TUS leads to varied functional connectivity changes, with six distinct time-courses of effects identified, and emphasized the importance of tracking brain changes over time and considering individual differences in responses to TUS.*
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  • Quantitative analysis of complex multi-cellular structures in living organisms is crucial for understanding their diverse 3D shapes, but traditional microscopy methods struggle due to tissue geometry.
  • A new FIJI plugin called VolumePeeler has been developed to facilitate virtual "peeling" of tissue layers, improving the visualization and analysis of 3D microscopy images.
  • VolumePeeler is freely available through the ImageJ/FIJI software platform, along with source code, examples, and tutorials for users.
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The human brain generates a rich repertoire of spatio-temporal activity patterns, which support a wide variety of motor and cognitive functions. These patterns of activity change with age in a multi-factorial manner. One of these factors is the variations in the brain's connectomics that occurs along the lifespan.

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Brain interdependencies can be studied from either a structural/anatomical perspective ("structural connectivity") or by considering statistical interdependencies ("functional connectivity" [FC]). Interestingly, while structural connectivity is by definition pairwise (white-matter fibers project from one region to another), FC is not. However, most FC analyses only focus on pairwise statistics and they neglect higher order interactions.

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Article Synopsis
  • The study investigates multistable behavior in neural networks, characterized by shifting between different synchronized states without external triggers, linked to how the brain processes new sensory information.
  • Key factors like network topology, delays, and noise significantly influence these dynamics, but the effects of local chaos versus stochasticity on state switching were previously underexplored.
  • Using a neural model, the research reveals that moderate levels of noise can enhance multistability in chaotic networks, while excessive noise disrupts it; interestingly, even nonchaotic networks can exhibit multistability under certain noise conditions.
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